Support for a third funding cycle of the predoctoral training Program entitled "Molecular and Cell Biology of Infectious Diseases". The training Program will be based in the Department of Molecular Genetics and Microbiology at Stony Brook University, 8 of whose faculty are proposed mentors. With an additional 12 outstanding faculty mentors from other University Departments, and nearby Brookhaven National Laboratories, the Program will train predoctoral students for a productive career in infectious disease research. Training will consist of lecture and laboratory courses in Genetics, Biochemistry, Molecular Biology, Cell Biology, Immunology, Microbial Pathogenesis and Scientific Ethics that will prepare students for thesis research. Students who show the most promise, based on their undergraduate academic performance and their achievements In graduate course work, laboratory rotations and qualifying exams, will be admitted to the Program beginning in the third year of graduate school for a 2- to 3-year period. All faculty mentors have a common interest in teaching and investigating the pathogenesis of infectious diseases at the molecular and cellular levels. All faculty mentors in the Program have individual NIH grants or other forms of support. The areas of thesis research training available to students include: a) bacterial pathogenesis;b) fungal virulence mechanisms;c) viral pathogenesis and replication;d) regulation of pathogen gene and protein expression;e) control of viral packaging and capsid assembly;f) development of diagnostics, drugs and vaccines against pathogens, g) innate immune responses to pathogens, and h) pathogenesis of Category A agents. The Program is overseen by a Director and Executive Committee and has a strong record of collaboration among faculty and students. The Program includes a robust mechanism for evaluating and improving all aspects of the training environment and for tracking the success of previous trainees for a period of up to 10 years. Nine of 10 trainees that have completed the Program since its inception remain in research/teaching positions and trainees generated 28 research publications during the period of support. The application requests support for 5 years, with 4 trainees requested in years 1-2, and 5 in years 3-5. RELEVANCE (See instructions): The MCBID Program will provide high-quality training in research and career development for predoctoral scientists. The ultimate goal is to foster the development of the future leaders in the field of infectious disease research.